1 files changed, 126 insertions, 0 deletions
diff --git a/test/Sema/tautological-unsigned-enum-zero-compare.c b/test/Sema/tautological-unsigned-enum-zero-compare.c
new file mode 100644
index 000000000000..a32cfcd8329f
--- /dev/null
+++ b/test/Sema/tautological-unsigned-enum-zero-compare.c
@@ -0,0 +1,126 @@
+// RUN: %clang_cc1 -triple=x86_64-pc-linux-gnu -fsyntax-only \
+// RUN:            -verify=unsigned,unsigned-signed %s
+// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only \
+// RUN:            -verify=unsigned-signed %s
+// RUN: %clang_cc1 -triple=x86_64-pc-win32 -fsyntax-only \
+// RUN:            -Wno-tautological-unsigned-enum-zero-compare \
+// RUN:            -verify=silence %s
+
+// Okay, this is where it gets complicated.
+// Then default enum sigdness is target-specific.
+// On windows, it is signed by default. We do not want to warn in that case.
+
+int main() {
+  enum A { A_a = 0 };
+  enum A a;
+  enum B { B_a = -1 };
+  enum B b;
+
+  // silence-no-diagnostics
+
+  if (a < 0) // unsigned-warning {{comparison of unsigned enum expression < 0 is always false}}
+    return 0;
+  if (0 >= a)
+    return 0;
+  if (a > 0)
+    return 0;
+  if (0 <= a) // unsigned-warning {{comparison of 0 <= unsigned enum expression is always true}}
+    return 0;
+  if (a <= 0)
+    return 0;
+  if (0 > a) // unsigned-warning {{comparison of 0 > unsigned enum expression is always false}}
+    return 0;
+  if (a >= 0) // unsigned-warning {{comparison of unsigned enum expression >= 0 is always true}}
+    return 0;
+  if (0 < a)
+    return 0;
+
+  if (a < 0U) // unsigned-signed-warning {{comparison of unsigned enum expression < 0 is always false}}
+    return 0;
+  if (0U >= a)
+    return 0;
+  if (a > 0U)
+    return 0;
+  if (0U <= a) // unsigned-signed-warning {{comparison of 0 <= unsigned enum expression is always true}}
+    return 0;
+  if (a <= 0U)
+    return 0;
+  if (0U > a) // unsigned-signed-warning {{comparison of 0 > unsigned enum expression is always false}}
+    return 0;
+  if (a >= 0U) // unsigned-signed-warning {{comparison of unsigned enum expression >= 0 is always true}}
+    return 0;
+  if (0U < a)
+    return 0;
+
+  if (b < 0)
+    return 0;
+  if (0 >= b)
+    return 0;
+  if (b > 0)
+    return 0;
+  if (0 <= b)
+    return 0;
+  if (b <= 0)
+    return 0;
+  if (0 > b)
+    return 0;
+  if (b >= 0)
+    return 0;
+  if (0 < b)
+    return 0;
+
+  if (b < 0U) // unsigned-signed-warning {{comparison of unsigned enum expression < 0 is always false}}
+    return 0;
+  if (0U >= b)
+    return 0;
+  if (b > 0U)
+    return 0;
+  if (0U <= b) // unsigned-signed-warning {{comparison of 0 <= unsigned enum expression is always true}}
+    return 0;
+  if (b <= 0U)
+    return 0;
+  if (0U > b) // unsigned-signed-warning {{comparison of 0 > unsigned enum expression is always false}}
+    return 0;
+  if (b >= 0U) // unsigned-signed-warning {{comparison of unsigned enum expression >= 0 is always true}}
+    return 0;
+  if (0U < b)
+    return 0;
+
+  if (a == 0)
+    return 0;
+  if (0 != a)
+    return 0;
+  if (a != 0)
+    return 0;
+  if (0 == a)
+    return 0;
+
+  if (a == 0U)
+    return 0;
+  if (0U != a)
+    return 0;
+  if (a != 0U)
+    return 0;
+  if (0U == a)
+    return 0;
+
+  if (b == 0)
+    return 0;
+  if (0 != b)
+    return 0;
+  if (b != 0)
+    return 0;
+  if (0 == b)
+    return 0;
+
+  if (b == 0U)
+    return 0;
+  if (0U != b)
+    return 0;
+  if (b != 0U)
+    return 0;
+  if (0U == b)
+    return 0;
+
+  return 1;
+}